Here is a summary of the NWP output for noon on Monday.
Issued 0441z, 26/05/11

The first half of the week will see showery (away from the SE) and
relatively cool WSW'lies giving way to a ridge from the south, with
temperatures rising through the latter half of the week. It's uncertain as
to whether the settled conditions will extend across the whole of the UK,
however, with NW Scotland in particular likely to stay breezy and perhaps
showery throughout.

Analysis and evolution to T+120 via GFS
Low pressure covers Northern Ireland, leading to SW'lies across much of the
UK. NW'lies cover the UK tomorrow as the low moves away to the NE, followed
by WSW'lies on Saturday. Sunday sees SW'lies ahead of a trough to the west.

T+120 synopsis
http://www.wetterzentrale.de/wz/pics/Rtavn12014.png
http://www.wetterzentrale.de/wz/pics/Rtavn1201.png
http://www.wetterzentrale.de/wz/pics/Rukm1201.gif
http://www.wetterzentrale.de/wz/pics/Recm1201.gif
http://www.wetterzentrale.de/wz/pics/Rjma1201.gif
The jetstream chart shows a strong and zonal jet across the Atlantic, with a
small trough over the UK. At the 500hPa level there's also a trough, with a
zonal flow upstream. MetO shows a trough to the west and SW'lies aloft, as
do the other runs.
At the surface the runs show WSW'lies with a low to the north.

Evolution to T+168
Days 6 and 7 with ECM show a ridge building across England and Wales with
southerlies elsewhere.
GFS brings WSW'lies on day 6 as a low crosses northern Scotland. Day 7 sees
SW'lies with a high to the south.

Looking further afield
Day 8 with ECM shows a ridge over England and Wales and southerlies
elsewhere. On day 9 there's a col and on day 10 northerlies associated with
a ridge to the west cover the UK.
GFS shows southerlies on day 8 from a high to the east. Day 9 sees a col for
all areas except Scotland, which lies under SW'lies. On day 10 WSW'lies
cover the UK as low pressure deepens to the NW.

Ensemble analysis
http://www.meteociel.com/cartes_obs/...&ville=Londres
The GEFS shows a marked rise in temperatures in a week's time.

ECM ensembles
http://www.meteogroup.co.uk/meteo/ep...tt6-london.gif
The ECM also shows warmer conditions in a week's time.